Step 1: STEP 1
open the program that comes.
click yes on the confirmation that comes, if you added a password, type it.
Step 2: STEP 2
Search for OEMBackground.
Step 3: STEP 3
Step 4: STEP 4
go to this location from windows explorer, by copying it and pasting it there
Step 5: STEP 5
create a new folder inside info named backgrounds
Step 6: ADDING THE PICTURE
place it inside the backgrounds folder that you created in the last step
THE PICTURE SHOULD BE LESS THAN 245KB IN SIZE
Step 7: AND YOU'RE DONE
if you want to remove it simply delete the picture from the backgrounds folder that you created and the default blue login wallpaper for win7 will be back.